A Case of Individual Variation of the Rhomboid Muscles M

Home , Levator scapulae muscle, Rhomboid muscles, Trapezius

A case of individual variation of the rhomboid muscles M. Ulkir1 , M.F. Sargon2

1Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey 2Department of Anatomy, Faculty of Medicine, Lokman Hekim University, Ankara, Turkey

[Received: 9 January 2020; Accepted: 1 February 2020]

During the routine gross anatomic dissection of a Turkish male cadaver; a variation of rhomboid muscles was observed on the left side. There were two rhomboid minors and three rhomboid majors coursing under the trapezius muscle. The origins of the upper and lower rhomboid minor muscles were C5, C6 and C7 vertebrae, respectively. Their insertions were to medial border of scapula, to upper part and to lower part of the spine of scapula, respectively. The origins of the upper, middle and lower rhomboid majors were C7, T1–T3 and T4–T5 vertebrae, respectively. Their insertions were to the 2/3 most inferior part of the medial border of scapula, from superior to inferior in sequence. In the examination of the literature, we could not observe such a variation of these muscles. In surgical procedures these types of variations have a clinical importance for intrathoracic muscle flap transfers and in cases with the paralysis of trapezius muscle. (Folia Morphol 2021; 80, 1: 222–224)

Key words: dissection, anatomy, cadaver

INTRODUCTION observed on the left side. There were two rhomboid The rhomboid minor and rhomboid major muscles minors and three rhomboid majors coursing under are inferior to levator scapulae muscle. Rhomboid the trapezius muscle. The origins of the upper and minor is a small, cylindrical muscle and rhomboid lower rhomboid minor muscles were C5, C6 and C7 major is a quadrilateral sheet of muscle [8]. These two vertebrae, respectively. Their insertions were to medial muscles work together to retract or pull the scapula border of scapula, to upper part and to lower part towards the vertebral column. With other muscles; of the spine of scapula, respectively. The origins of they may also rotate lateral aspect of the scapula the upper, middle and lower rhomboid majors were inferiorly [1]. In the literature; there are only a few C7, T1–T3 and T4–T5 vertebrae, respectively. Their reports related with the variation of these two mus- insertions were to the 2/3 most inferior part of the cles [4, 5, 9]. In the present case; to our knowledge, medial border of scapula, from superior to inferior we report a unique variation of these two muscles in sequence. In the examination of the literature, we on the left side of a cadaver. could not observe such a variation of these muscles. In the cadaver, the left superficial back muscles, the CASE REPORT right half of the hemithorax and right superficial During the routine gross anatomic dissection of back muscles were normal in every aspect (Fig. 1). the superficial back muscles of a 67-year-old Turkish There was any abnormality on the cadaver and it was male cadaver, a variation of rhomboid muscles was a healthy specimen.

Address for correspondence: M. Ulkir, MD, Hacettepe University, Faculty of Medicine, Department of Anatomy, Sihhiye. Altindag, Ankara, Turkey 06100, tel: +90 (542) 5341165, pbx: +90 (312) 3107169; e-mail: [email protected]

222 M. Ulkir, M.F. Sargon, Rhomboid muscle variation

quail-chick chimeras. Their results showed that the rhomboid muscles were made up of cells derived mainly from the lateral portion of the somite [7]. In animals: the rhomboid muscles always present cervical and thoracic parts and in carnivores there is an additional, capital part. Rhomboid muscles are innervated from the brachial plexus in the dog, but in some species they are also innervated by dorsal branches of local spinal nerves [2]. In the examination of the literature, our variation is unique and is clinically important. When found during surgical procedures, it can be used together with the usual rhomboid muscles for intrathoracic muscle flap transfers [3]. Additionally, the transfer of the rhomboid muscles to the infraspinous fossa (the Eden-Lange procedure) is important in cases with the paralysis of the trapezius muscle [6].

CONCLUSIONS In the literature, variations of rhomboid muscles are scarce. The present case report describes a variation of the rhomboid muscles. In surgical procedures

Figure 1. Variation of rhomboid muscles; 1, 2 — rhomboid minor these types of variations have a clinical importance muscles; a, b, c — rhomboid major muscles. for intrathoracic muscle flap transfers and in cases with the paralysis of trapezius muscle. DISCUSSION Acknowledgements The variations of the rhomboid muscles are The authors of this case report declare no relation- very rare. During the superficial back dissection of ships with any companies, whose products or services a 72-year-old male cadaver, Jelev and Landzhov [4] may be related to the subject matter of the article. No observed an aberrant muscle bilaterally below the complex statistical methods were necessary for this pa- lower border of the rhomboideus major. The unu- per. The cadaver belongs to the Hacettepe University, sual muscle arose by a thin aponeurosis from the Faculty of Medicine, Department of Anatomy, Turkey. spinous process of the mid-thoracic vertebrae and was attached laterally to the lowest part of the medial References border of the scapula [4]. In the study of Mori [5], 1. Chang KV, Wu WT, Mezian K, et al. Sonoanatomy of a muscular slip called “musculus rhomboideus minus” muscles attaching to the medial scapular border (levator was described in 11–14% of the Japanese population. scapulae, rhomboid minor, and serratus anterior) revis- This muscle was originated from the spinous process ited. Am J Phys Med Rehabil. 2019; 98(7): e79–e80, doi: 10.1097/PHM.0000000000001136, indexed in Pubmed: above the latissimus dorsi origin, was coursing later- 30640725. ally and gradually disappearing or passing into the 2. Dyce KM, Sack WO, Wensing CJG. Textbook of Veterinary fascia of the teres major muscle [5]. Von Haffner [9] Anatomy. 4. ed. Saunders 2009: p. 84. observed a small muscle on the right side of a cadaver, 3. Grima R, Krassas A, Bagan P, et al. Treatment of complicat- stretched between the sixth thoracic vertebra and ed pulmonary aspergillomas with cavernostomy and muscle flap: interest of concomitant limited thoracoplasty. Eur the inferior angle of the scapula. The author named J Cardiothorac Surg. 2009; 36(5): 910–913, doi: 10.1016/j. this muscle as “musculus rhomboideus minimus”. ejcts.2009.05.007, indexed in Pubmed: 19595606. Additionally, in his case, bilateral incomplete agenesis 4. Jelev L, Landzhov B. A rare muscular variation: the third of of the trapezius muscles was present [9]. In another the rhomboids. Anatomy. 2013; 6-7: 63–64, doi: 10.2399/ ana.11.218. study, Saberi et al. [7] investigated the embryonic 5. Mori M. Statistics on the musculature of the Japanese. origins of the rhomboid muscles by following the Okajimas Folia Anat Jpn. 1964; 40: 195–300, doi: 10.2535/ derivatives of medial and lateral somite halves using ofaj1936.40.3_195, indexed in Pubmed: 14213705.

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